Loading assembly for a vehicle spindle test fixture

ABSTRACT

A loading assembly for a vehicle spindle test fixture includes a belt crank that pivots on a first axis to differentially displace two vertical struts which are attached to a wheel adapter housing in order to apply a braking moment to the vehicle spindle. A lever pivotally supported about a second axis is pivotally joined to the bell crank and is used to displace the bell crank, the vertical struts and the wheel adapter housing to apply a vertical force. A control link controls rotation of the bell crank about the first axis and is pivotally joined to the bell crank about a third axis. A second lever is pivotally supported for movement about the second axis and is pivotally joined to an end of the control link about a fourth axis. When a trailing arm suspension is to be tested, the bell crank, the first lever, the control link and the second lever are arranged to form a non-parallelogram linkage in order to induce a brake axis rotation when a vertical displacement is applied.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 08/337,610,U.S. Pat. No. 5,533,403 filed Nov. 10, 1994.

BACKGROUND OF THE INVENTION

The present invention relates to loading assemblies used for testingportions of a vehicle. More particularly, the present invention relatesto a loading assembly for applying selected forces and moments to avehicle spindle, the loading assembly being adaptable to various vehiclesuspensions.

Many test fixtures have been advanced to apply forces and moments to avehicle spindle in order to simulate driving or road conditions. Thesetest fixtures often include separate actuators to apply vertical,longitudinal and lateral forces as well as braking moments to thevehicle spindle. U.S. Pat. Nos. 4,733,558 and 5,083,453 disclose twosuch test fixtures.

Commonly, the test fixtures include a wheel adapter housing that ismounted to the vehicle spindle in place of a wheel and tire assembly.Two vertical struts are joined to the perimeter of the wheel adapterhousing and are used to transfer the longitudinal forces, the verticalforces and the braking moments to the vehicle spindle. A centerdownwardly projecting tang located between the vertical struts and alsorigidly joined to the perimeter of the wheel adapter housing is joinedto a lateral strut. An actuator is joined to the lateral strut andapplies loads to the vehicle spindle that are generally perpendicular tothe vertical struts.

Although the above-identified test fixtures are quite capable ofapplying longitudinal forces, vertical forces, lateral forces andbraking moments to the vehicle spindle, some crosstalk which is theapplication of an unintended force in one direction through theapplication of an intended force in another direction exists. Forexample, when a lateral load is applied to the wheel adapter housingwhile the wheel adapter housing undergoes displacement about the vehiclespindle axis, an unintended braking moment is also developed. Similarly,an unintended longitudinal force is developed when a lateral load isapplied to the wheel adapter housing with longitudinal displacement ofthe wheel adapter housing.

SUMMARY OF THE INVENTION

The present invention relates to a loading assembly used in vehiclespindle test fixtures to apply selected forces and moments to a vehiclespindle of a vehicle under test. In a first embodiment, the loadingassembly includes a wheel adapter housing that is operably connected toa first actuator for applying forces along a first axis and a secondactuator for applying a braking moment about an axis of the spindle,which is generally perpendicular to the first axis. A third actuatorapplies lateral forces to the wheel adapter housing. The loadingassembly reduces crosstalk between forces applied in the lateraldirection and unintended forces applied along the first axis, and forcesapplied in the lateral direction and unintended braking moments.

In a second embodiment, the loading assembly is adaptable to trailingarm suspensions wherein a brake axis rotation is developedsimultaneously when a vertical displacement is applied. In a preferredform of this embodiment, a bell crank pivots on an axis todifferentially displace two vertical struts which are attached to thewheel adapter housing in order to apply a braking moment. A leverpivotally supported about a second axis is pivotally joined to the bellcrank and is used to displace the bell crank, the vertical struts andthe wheel adapter housing to apply a vertical force. A control linkcontrols rotation of the bell crank about the first axis and ispivotally joined to the bell crank about a third axis. A second lever ispivotally supported for movement about the second axis and is pivotallyjoined to an end of the control link about a fourth axis. When atrailing arm suspension is to be tested, the bell crank, the firstlever, the control link and the second lever are arranged to form anon-parallelogram linkage in order to induce a brake axis rotation whena vertical displacement is applied. In a preferred embodiment, ifdesired, the bell crank, the first lever, the control link and thesecond lever can be arranged to form a parallelogram linkage so that abraking moment is not induced when a vertical force is applied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle spindle test fixture includinga loading assembly of the present invention;

FIG. 2 is a perspective view of a first embodiment of a wheel adapterhousing with parts in section and parts broken away;

FIG. 3 is a front elevational view of a loading member for the wheeladapter housing illustrated in FIG. 2;

FIG. 4 is a side elevational view of the loading member of FIG. 3;

FIG. 5 is a perspective view of a second embodiment of a wheel adapterhousing with parts in section and parts broken away;

FIG. 6 is a front elevational view of a loading member for the wheeladapter housing illustrated in FIG. 5;

FIG. 7 is a schematic perspective view of a third embodiment of a wheeladapter housing;

FIG. 8 is a sectional view of the third embodiment taken along lines8--8 of FIG. 7;

FIG. 9 is a perspective view of a fourth embodiment of a wheel adapterhousing;

FIG. 10 is a perspective view of the embodiment of FIG. 1 with partsbroken away; and

FIG. 11 is a perspective view of the embodiment of FIG. 1 with partsbroken away.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a vehicle spindle test fixture generally at 10. Thevehicle spindle test fixture 10 is designed for applying linear forcesand rotational moments to a spindle 12 of a vehicle 14. The vehiclespindle test fixture 10 includes a first embodiment of a wheel adapterhousing 16 that is suitably fixed to the vehicle spindle 12. A firstloading assembly 18 is joined to the wheel adapter housing 16 using apair of vertically extending loading links or struts 20. Generally, thefirst loading assembly 18 applies loads to the wheel adapter housing 16,and thus the spindle 12, in directions parallel to two mutuallyperpendicular axes 22 and 24. In addition, the first loading assembly 18applies a rotational moment or torque about an axis 26 that is mutuallyperpendicular to axes 22 and 24. A second loading assembly is indicatedat 28. The second loading assembly 28 applies a force to the wheeladapter housing 16 in a direction parallel to axis 26.

As used herein, the following definitions for forces and moments aboutthe axes 22, 24 and 26 will apply:

A "longitudinal force" is a force applied to the wheel adapter housing16 generally parallel to the axis 22, the axis 22 being parallel to alongitudinal axis 21 of the vehicle 14;

A "vertical force" is a force applied to the wheel adapter housing 16generally parallel to the axis 24;

A "lateral force" is a force applied to the wheel adapter housing 16generally parallel to the axis 26 and an axis of the spindle 12;

A "braking moment" is a moment applied to the wheel adapter housing 16generally about the axis 26; and

A "steer moment" is a moment applied to the wheel adapter housing 16generally about the axis 24.

An enlarged view of the wheel adapter housing 16 is illustrated in FIG.2. The wheel adapter housing 16 is mounted to the vertical struts 20using suitable spherical joints indicated at 40A and 40B. The wheeladapter housing 16 includes a first loading member indicated at 42 thatis secured to the vehicle spindle 12. Using the struts 20 and the firstloading assembly 18 illustrated in FIG. 1, longitudinal forces, verticalforces and braking moments are applied directly to the first loadingmember 42, which in turn, are then applied to the vehicle spindle 12.

A second loading member 44 receives forces generally parallel to theaxis 26 from a lateral strut 46. In the embodiment illustrated in FIG.2, a bearing assembly 48 joins the second loading member 44 to the firstloading member 42. The bearing assembly 48 is substantially rigid forforces applied to the second loading member 44 that are parallel to theaxis 26 in order to transfer these forces to the first loading member42, while allowing movement of the second loading member 44 relative tothe first loading member 42 for braking moments and longitudinal forcesapplied to the first loading member 42. Since the second loading member44 is able to move relative to the first loading member 42, themagnitude of unintended braking moments or unintended longitudinalforces with application of lateral forces is reduced.

In the embodiment illustrated in FIG. 2, the first loading member 42includes two end sections 50 and 52. The end section 50 includes anoutwardly facing flange portion 56 and a cylindrically extending portion58 joined to the extending flange portion 56 and preferably madeintegral therewith. The end section 52 is similar having an outwardlyfacing flange portion 60 and an integral cylindrically extending portion62. A plurality of bolts, one of which is indicated at 54, joins theextending portion 58 of the end section 50 to the extending portion 62of the end section 52. A mounting plate 66 is disposed in an innerannular recess 68 of the end section 52 and is secured thereto with aplurality of suitable bolts 72. The mounting plate 66 includes a centeraperture 71 for receiving a center portion 73 of the spindle 12.Apertures 74 located around the center aperture 71 receive lugbolts, notshown, present on the spindle 12. The lugbolts are used to secure thewheel adapter housing 16 to the spindle 12.

The second loading member 44 includes a first support collar indicatedat 80 having an extending plate portion 82, and a second support collar86. A plurality of bolts indicated at 90 fasten the first support collar80 to the second support collar 86. As illustrated, inner diameters ofthe support collars 80 and 86 are slightly larger than the outerdiameters of the outer surfaces of extending portions 58 and 62 so thatannular gaps 81 and 83 are formed therebetween. Each support collar 80and 86 includes an L-shaped annular recess 85 and 87, respectively. Whenthe support collars 80 and 86 are secured together the recesses 85 and87 form a channel 89 facing the extending portions 58 and 62. Theextending portions 58 and 62 also include L-shaped annular recesses 91and 93, respectively. Accordingly, when the end sections 50 and 52 arejoined together, the annular recess 91 and 93 form a channel 9S facingthe channel 89.

The bearing assembly 48 mounts within the channels 89 and 9S wherein anouter bearing race 100 is mounted in the channel 89 and a inner bearingrace 102 is mounted within the channel 95. Specifically, the endsections 50 and 52 are clamped to the inner bearing race 102 with bolts54, while the support collars 80 and 86 are clamped to the outer bearingrace 100 with bolts 90. Suitable bearing elements indicated at 104 areprovided and allow relative rotational movement of the races 100 and102. The bearing assembly 48 acts as a thrust bearing transferringlateral forces received by the second loading member 44 to the firstloading member 42, while allowing the second loading member 44 to rotatefreely about the first loading member 42 when longitudinal forces orbraking moments are applied.

An adjustable coupling assembly indicated at 110 transfers lateralforces from the lateral strut 46 to the extending plate 82 of thesupport collar 80. A suitable rod end 112 mounted to the end of strut 46is pinned, and pivots between plates 114 and 116 of the adjustablecoupling assembly 110. Fasteners 120 project through vertical slots 118Aand 118B (FIG. 4) provided in the extending plate 82 and secure theplates 114,116 and the rod end 112 at a selected radial distance fromthe axis of the spindle 12 when the wheel adapter housing 16 is mountedthereto. By adjusting the position of the adjustable coupling assembly110 on the extending plate 82, the wheel adapter housing 16 can emulatewheel and tire assemblies of various diameters.

Preferably, as illustrated in FIG. 4, the extending plate 82 is thinnerthan, or offset from, an annular portion 83 that encircles the extendingportion 58 of the end section 50. By making the extending plate 82thinner or offset, symmetry is established in the wheel adapter housing16 so that a pivot axis 113 of rod end 112 is located in a center plane115 of the wheel adapter housing 116. By locating the pivot axis 113 inthe center of plane 115, proper emulation of a tire contact patch with aroad surface is achieved.

An idler or stabilizing strut indicated at 119 in FIGS. 1 and 2 ispivotally connected between the extending plate 82 and a lever 122 ofthe first loading assembly 18. As illustrated in FIG. 2, the idler strut119 includes a suitable rod end 121 that is pivotable about a shaft 123joined to the extending plate 82. A servo controlled hydraulic actuator125 is joined to the lever 122 and pivots the lever 122 about a pivotshaft 127 to develop the longitudinal forces. It should be understoodthat although hydraulic actuators are depicted and described in thisembodiment and the embodiments below, other suitable actuators such aspneumatic and electric actuators can also be used. The actuator 125 ispivotally supported on a frame 131 having support legs 133A and 133B.The longitudinal forces are transferred to the wheel adapter housing 16through longitudinal struts 124 and 126 which are connected to a crossbeam 128 through a suitable spherical joint 130. The cross beam 128 isin turn connected to each of the vertical struts 20 using suitablespherical joints indicated at 132 and 134. The idler strut 119 helpsmaintain the lateral input point (adjustable coupling assembly 110) forthe extending plate 82 of the support collar 80 below the axis of thespindle 12 during longitudinal displacement of the wheel adapter housing16. The idler strut 119 also reacts the longitudinal forces induced whenlateral forces are applied during longitudinal displacement of the wheeladapter housing 16 due to the plan view angle between the lateral inputstrut 46 and the wheel adapter housing 16. If an idler pivot 119A,longitudinal input lever pivots 124A and 126A, and pivot shaft 127 onlever 122 are positioned from one another to mimic pivots 40A and 40B,pivots 132 and 134 and pivots 252 and 254 (discussed below), on thevertical struts 20, respectively, the crosstalk problems (positionerrors) between longitudinal displacement and the longitudinal positionof the lateral input strut 46 are minimized.

A second embodiment of a wheel adapter housing 150 is illustrated inFIG. 5. The wheel adapter housing 150 is similar to the wheel adapterhousing 16 described above wherein like reference numbers have been usedto identify identical elements. In addition to receiving and applyinglateral forces generally parallel to the axis 26, the wheel adapterhousing 150 transmits steering moments to the spindle 12. The wheeladapter housing 150 includes a second loading member 152 having a firstsupport collar 154 with two extending portions illustrated at 156 and158. Each extending portion 156 and 158 receives lateral forcestransmitted through corresponding lateral struts 160 and 162,respectively. The first support collar 154 is secured to the secondsupport collar 86 and the bearing assembly 48 as described above. Asteering moment is transmitted to the spindle 12 when opposed lateralforces, for example as indicated by arrows 164 and 166, are transmittedthrough the struts 160 and 162, the opposed lateral forces beinggenerated from a suitable actuator assembly, not shown.

The first support collar 154 is illustrated in FIG. 6. Adjustablecoupling assemblies 168 and 170 similar to the adjustable couplingassembly 110 described above attach the struts 160 and 162,respectively, to the first support collar 154. Slots 180 and slots 182provided in the extending portions 156 and 158, respectively, allow thepositions of the adjustable coupling assemblies 168 and 170 to beadjusted relative to the axis of spindle 12. As illustrated in FIG. 5,the idler strut 119 is attached to the extending portion 156 using amounting shaft 171.

A third embodiment of the wheel adapter housing 200 is illustrated inFIGS. 7 and 8. The wheel adapter housing 200 is schematicallyillustrated in these Figures and includes a first loading memberindicated at 202 that is attached to the vertical struts with suitablespherical bearings mounted at opposed ends 204 and 206. As with theprevious wheel adapter housings described above, the first loadingmember 202 receives longitudinal forces, vertical forces and brakingmoments from the vertical struts, and transfers these loads directly tothe vehicle spindle 12.

A second loading member indicated at 210 is pivotally attached to thefirst loading member 202 with a suitable pivot pin 205. The secondloading member 210 includes flanges 214A and 214B that extend overopposed surfaces of the first loading member 202. A support portion 216extends away from the flanges 214A and 214B and includes a slot 220. Thelateral strut 46 illustrated in FIG. 2 is joined to the second loadingmember 210 with a suitable pivot connection using the slot 220. The slot220 allows the coupling of the lateral strut 46 with the second loadingmember 210 to be adjusted in order to emulate wheel and tire assembliesof various diameters.

If steer forces are desired, a second loading member 230 illustrated inFIG. 9 can be used. The second loading member 230 also includes flanges232A and 232B that extend over opposed surfaces of the first loadingmember 202. The pivot pin 205 joins the second loading member 230 to thefirst loading member 202 and allows limited pivoting movementtherebetween. The lateral struts 160 and 162 illustrated in FIG. 5 arejoined at spaced apart locations 236 and 238, respectively, so as todevelop the desired steer moments. As with the embodiments of FIGS. 1, 2and 5, the idler strut 119 is connected to the lever 122 of the firstloading assembly and maintains the input of the lateral force below axis26. The embodiment of FIGS. 7, 8 and 9 illustrate that crosstalk betweenthe lateral forces and braking moments, and the lateral forces andlongitudinal forces can also be reduced by the use of the pivot pin 205that is spaced-apart from the axis 26 or the axis of the vehiclespindle.

Another aspect of the present invention is the ability to simulatetrailing arm suspensions. Referring to FIG. 10, wherein the secondloading assembly 28 has been removed for clarity. A braking moment isapplied to the wheel adapter housing 16 through a differential movementof the vertical struts 20. Specifically, the lower end of the verticalstruts 20 are joined with a delta-shaped (triangular) bell crank 250.The struts 20 are connected to the bell crank 250 at suitable pivots 252and 254. The pivots 252 and 254 are spaced in a longitudinal directionto be equal to the pivots 132 and 134 of the cross beam 128 and thepivots of the wheel adapter housing 16 so that the struts 20 aresubstantially straight. Load cells 258 and 260 are provided in eachstrut 20 to directly measure forces transmitted therethrough.

The bell crank 250 is movable in a vertical direction to apply verticalloads simultaneously to both of the vertical struts 20. The bell crank250 is mounted on a bell crank arm assembly 261 which comprises twospaced-apart plates 262 and 264 that move as a unit. The plates 262 and264 have outer ends 266 and 268, respectively, that are connected with apin 270 that passes through the center of the bell crank 250. The bellcrank arm assembly 261 in turn has an actuating arm portion 274 and issupported on the frame member 131 with a pivot pin 278. It should beunderstood that the bell crank 250 and plates 262 and 264 do not contactsupport legs 133A or 133B (FIG. 1).

Referring to FIG. 11, the plates 262 and 264 are joined together with ashaft 280. A vertical actuator 282 is pivotally joined to the shaft at arod end 284. The actuator 282 is a double acting, servo-controlledhydraulic actuator and has its base end connected to a support pedestal286. Extension and retraction of the rod of actuator 282 causes rotationof the bell crank arm assembly 261 about the pin 270 and thus the bellcrank 250 to move in a vertical direction to load both struts 20 and inturn apply loads to the wheel adapter housing 16.

A braking moment is applied to the wheel adapter housing 16 by pivotingthe bell crank 250 about its pivot pin 270 and causing differentialvertical movement of the vertical struts 20 through movement of acontrol link 290. The control link 290 is pivotally connected with pivotpin 292 to a lower end of the bell crank 250. At an end opposite bellcrank 250, the control link 290 is pivotally joined to an actuator lever294 with pin 295. The actuator lever 294 has one end 296 pivotallymounted on the same pivot axis as the bell crank arm assembly 261, or inother words, on the pivot pin 278. The lever 294 is mounted to haveindependent pivotal movement relative to the bell arm crank assembly261.

The lever 294 is controlled with a servo-controlled hydraulic actuator298 that has an extendable and retractable rod 300. An outer end of rod300 is connected to the lever 294 with a pivot pin 302. A base end ofthe actuator 298 is connected to the pedestal 286. Upon movement of theactuator rod 300, the lever 294 will cause displacement of the controllink 290 and pivotal movement of the bell crank 250 about pivot pin 270,which in turn, causes one of the vertical struts 20 to move upwardlywhile the other vertical strut moves downwardly.

The system described above is versatile in that it can be used to testvarious types of suspensions including trailing arm suspensions. Unlikeother forms of suspensions, trailing arm suspensions induce a brakingmoment with application of a vertical force. In a first embodiment, abrake axis rotation is induced when a vertical displacement is appliedby making a non-parallelogram linkage of elements between the pivot pins270 and 278 of the bell crank arm assembly 261 and the pivot pins 292and 295 of the control link 290. As illustrated in FIG. 10, the lever294 includes a plurality of mounting apertures 310 for the pivot pin 295of the control link 290. For example, to simulate a trailing armsuspension, the pivot pin of control link 290 can be moved to mountingaperture 312. If a nontrailing arm suspension is to be tested, thecontrol link 290 is moved to aperture 314 so as to establish aparallelogram linkage between pivot 270, 278, 292 and 295.

It should be understood that use of the lever 294 with mountingapertures 310 is but one embodiment for simulating trailing armsuspensions. Alternatively, the control link 290 can be adjustable inlength so as to adjust the distance between pivot pins 292 and 295.Likewise, the length of any elements between pivot pins 270, 278, 292and 295 can be made adjustable. In another embodiment, the actuator 298can have an adjustable zero point so that, for example, if a trailingarm suspension is to be tested, a zero point is established so that therod 290 is slightly retracted and when a vertical force is applied tolift the bell crank 250, the actuator 298 is maintained at the zeropoint thereby causing pivotal movement of the bell crank 250 withvertical displacement of the bell crank 250.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A loading apparatus used in a vehicle spindletest fixture to apply forces to a vehicle spindle having a vehiclespindle axis, the loading apparatus comprising:a wheel adapter housingattachable to the vehicle spindle; a pair of struts connected to thewheel adapter housing; a bell crank operably connected to the strutsremote from the wheel adapter housing; and means for displacing the bellcrank so as to displace the wheel adapter housing in a direction ofdisplacement of the bell crank while simultaneously causing rotation ofthe bell crank based upon displacement of the bell crank in thedirection of displacement to differentially move the struts to develop amoment on the wheel adapter housing about the vehicle spindle axis. 2.The loading apparatus of claim 1 wherein the means for displacingcomprises a linkage including a lever pivotally joined to the bell crankfor pivotable movement about a first pivot axis, the lever beingsupported for pivotable movement about a second pivot axis; and acontrol link pivotally joined to the bell crank for pivotable movementabout a third axis, the control link pivotable about a fourth axis;wherein a distance between the first pivot axis and the second pivotaxis is not equal to a distance between the third pivot axis and thefourth pivot axis.
 3. The loading apparatus of claim 2 and furthercomprising a second lever pivotally connected to the control link forpivotable movement about the fourth pivot axis, the second lever beingsupported for pivotable movement about the second pivot axis; whereinthe bell crank, the first-mentioned lever, the control link and thesecond lever form a non-parallelogram linkage.
 4. The loading apparatusof claim 3 and wherein the second lever includes a plurality ofapertures for selectively relocating the fourth pivot axis.
 5. Theloading apparatus of claim 3 and wherein a length of the control link isadjustable.
 6. The loading apparatus of claim 1 wherein the wheeladapter housing comprises:a first loading member joined to the pair ofstruts and securable to the vehicle spindle for receiving andtransferring a first force to the vehicle spindle parallel to a firstaxis that is perpendicular to the vehicle spindle axis, and a secondforce to the vehicle spindle parallel to a second axis that isperpendicular to the first axis and the vehicle spindle axis; a secondloading member for receiving and transferring forces generally parallelto the vehicle spindle axis; and means for connecting the first loadingmember to the second loading member to transfer said forces parallel tothe vehicle spindle axis to the first loading member and allowing atleast partial rotation of the second loading member about the firstloading member.
 7. The loading apparatus of claim 6 wherein the meansfor connecting comprises a pivot pin.
 8. The loading apparatus of claim6 wherein the means for connecting comprises a bearing assembly.
 9. Theloading apparatus of claim 8 wherein the bearing assembly includes afirst bearing race joined to the first loading member, a second bearingrace joined to the second loading member and a plurality of bearingsinterposed between the first bearing race and the second bearing race.10. The loading apparatus of claim 8 wherein the first loading membercomprises a plate portion fastened to the vehicle spindle and acylindrical portion extending outwardly from the plate portion and aboutthe vehicle spindle axis, and wherein the bearing assembly includes abearing race joined to the cylindrical portion.
 11. A loading apparatusused in a vehicle spindle test fixture to apply forces to a vehiclespindle having a vehicle spindle axis, the loading apparatuscomprising:a wheel adapter housing attachable to the vehicle spindle; apair of struts connected to the wheel adapter housing; a bell crankoperably connected to the struts remote from the wheel adapter housing;and a linkage including a first lever pivotally joined to the bell crankfor pivotable movement about a first pivot axis, the lever beingsupported for pivotable movement about a second pivot axis; a controllink pivotally joined to the bell crank for pivotable movement about athird axis, the control link pivotable about a fourth axis; and a secondlever pivotally connected to the control link for pivotable movementabout the fourth pivot axis, the second lever being supported forpivotable movement about the second pivot axis; wherein the bell crank,the first lever, the control link and the second lever selectively forma non-parallelogram linkage.
 12. The loading apparatus of claim 11 andwherein the second lever includes a plurality of apertures forselectively relocating the fourth pivot axis.
 13. The loading apparatusof claim 11 and wherein a length of the control link is adjustable. 14.The loading apparatus of claim 11 wherein the wheel adapter housingcomprises:a first loading member joined to the pair of struts andsecurable to the vehicle spindle for receiving and transferring a firstforce to the vehicle spindle parallel to a first axis that isperpendicular to the vehicle spindle axis, and a second force to thevehicle spindle parallel to a second axis that is perpendicular to thefirst axis and the vehicle spindle axis; a second loading member forreceiving and transferring forces generally parallel to the vehiclespindle axis; and means for connecting the first loading member to thesecond loading member to transfer said forces parallel to the vehiclespindle axis to the first loading member and allowing at least partialrotation of the second loading member about the first loading member.15. The loading apparatus of claim 14 wherein an axis of pivotalmovement of the second loading member relative to the first loadingmember is spaced-apart from the vehicle spindle axis.
 16. The loadingapparatus of claim 14 wherein an axis of pivotal movement of the secondloading member relative to the first loading member is the vehiclespindle axis.
 17. The loading apparatus of claim 14 wherein the meansfor connecting comprises a pivot pin.
 18. The loading apparatus of claim14 wherein the means for connecting comprises a bearing assembly. 19.The loading apparatus of claim 18 wherein the bearing assembly includesa first bearing race joined to the first loading member, a secondbearing race joined to the second loading member and a plurality ofbearings interposed between the first bearing race and the secondbearing race.
 20. The loading apparatus of claim 18 wherein the firstloading member comprises a plate portion fastened to the vehicle spindleand a cylindrical portion extending outwardly from the plate portion andabout the vehicle spindle axis, and wherein the bearing assemblyincludes a bearing race joined to the cylindrical portion.